Ok, I use only dry yeast (nottingham, etc). I usually end up pitching when the wort is about 80-90*F. This is because I don't have a chiller, and just put my brewpot into the sink (cold water bath) to chill. I can get it down to 90 or so in 1/2 hour, but I get impatient after that, and put it into the carboy, then pitch, figuring that if I'm hydrating the yeast in 100*F water, that it can handle going into 90*F wort.

The closer to your yeast's fermentation range the better. Too high a fermentation temp is going to give you off flavors (ie. fusel alcohols, which will give you a rippin' headache) and the wort tends to pick up temperature as the yeast becomes more active as well.

For ales I pitch at around 65°. For lagers I try to get the wort to about 45-50° before pitching.

Due to the fact that I live in a very warm climate I've begun lowering my pitch temps, as most of the off flavors are produced during the beginning of fermentation. I pitch my ales @52/55 and lagers about 45 and let them ramp up to desired temps over a day or so